Gear



Patented Feb. 26, 1924.

ROGER D. BABSON, F SPRINGFIELD, MASSACHUSETTS, ASSIGIIOR TO BAUSH IiIACHmE TGOL COMPANY, COR-POBATIGN OF MASSACHUSETTS.

GEAR.

13' 0 Drawing.

2" 0 all whom it may concern:

Be it known that ROGER D. BABSON, a citizen of the United States, and resident oi Springfield, Massachusetts, have invented certain new and useful Improvements in Gears, of which the following is a. specification.

In my Patent No. 1,371,214, of March 15,

1921, I have described a gear made of analuminum alloy which is forged or otherwise worked and is heat treated and which by this working and heat treatment has its physical qualities very substantially improved.

The specific alloy referred to in the said patent consists of 91% aluminum, 0.5% magnesiuin and the balance manganese and copper, with chromium optional; the chromium being said to be less important than the other ingredients.

I have found, however, by experiment that the use of chromium is of particular importance and that a composition containing it produces a better gear than without it. It improves the bearing quality of the metal and the smooth and silent runningof the gear. My present invention, therefore, is directed to a gear made of an alloy chiefly of aluminum and having chromium as an essential element, the alloy being forged or otherwise worked and heat treated and being, of course, capable of improvement in its physical properties by these operations. 7

A suitable alloy consists of aluminum about 949/0 to 96%, copper about 2.5% to 4%, chromium and manganese taken together about 1%, and the balance magnesium. As the percentage of aluminum is increased the percentage of copper should generally be reduced, and a similar inverse relation should exist with respect to the manganese and chromium.

In order to secure the best results I have found that the variations referred to should- Application' filed November 30, 1921. Serial N 0. 518,995.

be kept within certain limits.v The minimum for the copper should be 2% and the maximum limit The magnesium content should be than 1%. The combined manganese and chromium content should be about 1% or less.

In making gears of this alloy I may proceed as follows: The alloy is cast into ingots, rolled or forged into billets and then cut and forged into blanks in the form of rings and these rings drop forged. This Working of the metal increases the tensile strength. treated, as by heating them to a temperature approximating 500 to 550 degrees centigrade and quenched; which heat treatment increases the tensile strength, elastic limit and The forged rings are thenheat other physical properties until it has approximately the strength of steel. After the heat treatment an ageing of the metal for several days is required to bring it up to the desired tests. It may be again forged before cutting or machining into a, gear.

I have found by considerable experimentation that this alloy produces very excellent timing gears for automobiles and that the added chromium gives an increased bearing quality and durability and quietness which are particularly important in this class of gears. The same qualities also are extremely valuable in worms and worm gears and other types of earin What I claim is: g g

A gear composed of an alloy consisting chiefly of aluminum and containing copper, magnesium, manganese and chromium, which alloy has been Worked and heat treated, the magnesium being'less than 1%, the copper being 2%,to 5% and the chromium and manganese taken together being about 1% or less of the composition.

In witness whereof, I have hereunto signed my name.

ROGER D. B-ABSON. 

